Timing mechanism



C. A. MAYER TIMING MECHANISM July 31, 1923.

Filed Feb. 18. 1921 3 nuawtoz Car/ August Mayer afiom AA. ,4

Patented July 31, 1923.

UNITED STATES PATENT OFFICE. y

CARL AUGUST MAYEI1, OF SPRINGFIELD, MASSACHUSETTS, ASSIGNOB TO AMERIOAN BOSCH MAGNETO CORPORATION, -OF SPRINGFIELD, MASSACHUSETTS, A CORPO- BATION OF NEW-YORK.

TIMING MECHANISM.

, Application filed February 18, 1921. Serial No. 446,140.

To all wlwm itrmay co'neem: j

Be it known that I, Cauunoeusr MAYER, a citizen of the United States, residing at Springfield pin the county of Hampden, State of as i chusetts, have invented certain new and useful Improvements in Timing Mechanism; and I do, hereby declare the following to be a, full, clear,I and exact description of the inventiomsuch as w ll enable others skilled in the art to which it appertains to make and use the same.

,Thepresent invention relates to an ,adjustable timing device for magnetos, and particularly one adapted to be carried by the interrupter, housing of thevmagneto.

An ignition system almost invariably provides variabletiming periods to suit different speedand load, conditions imposed u on the engine with which it is associated.

0 that en c'l, the.mechanical interrupter of the :magneto or sparking coil, has an adj ustable member to which; is attached, atiming' member connected by' an adjusting rod or Wireidthecontrol lever. on the steering wheel. or postpf an; automotive vehicle or; a convenient part of a stationary prganization. U eretofore, it has-been customarytto fasten a .timing arm to. the; adjustable member of the interrupter ,by a screw or other securing means for rigidly connecting them together, but in such arrangement the adjusting pull i, the control lever isappliedat a single pt ntwf the ;periphery of the adjustable member and sometimes causes the adjust- I able member to bindinits bearing, particularly if a ;decided.increase in the resistance develops in the bearing.

It is often necessary for the-timing member to be located on one side or the other of the adjustable member ofthe interrupter, or above or below it, or at some intermediate point, in order that the control lever may be attached to it most conveniently. The ad justable member is ordinarily in the form of a ring carrying cams which arev periodically engaged by the defiectable element of a pair of contact carrying elements. These cams aregaccurately positioned and fastened in the adjustable member,-or cam ring, by the manufacturerv of the interrupter, and therefore, the engine builder is frequently inconvenienced in installin the magneto or the adj ustingrod or wire. Io meet this dif ficulty, the adjustable .member or cam ring of the interrupter has been provided with slots' into a selected oneof which is seta lug thicker adjustable member to provide forv the slots. Th1s.results, as before, in asinglepoint of. application of the adjusting pull the adjustable member. Furthermore, the tuning ring is not'positively preventedfrom working off from the adjustable member in an axial direction as a result of the continual vibration to which it is subjected by the engine. i

The timing ring is nsually rigid or integral With the timing arm, both having a common radial slit to ermitc .a, certain amount of flexing of the ring halvesand the arm portionson each side ofi thelislit the arm. A clamping screw is used to flex the parts so as to clamp the ringvhalves upon the periphery of the cam ring. The pressure thus applied by the timing ring upon the cam ring forces the latter out of the true circular shape and a uniform result can never be'produced due to the eccentricity of the rings upon the contraction of the split timing ring. Furthermore, such timing ring can gri the cam ring at only two points, or

but a ew points, around its circumference instead of substantially the whole circumferenceior periphery thereof. Such structure cannot meet the re uir'ements of providin a connection adapted for all desired angu ar relations between the timing arm and the adjustable interrupter element nor the precise co-operation necessarily required in a magneto between the stationary and rotatable elements of the interrupter.

-With the above in view and with the object of producing a simpler, cheaper and more ef'ficient device, I have in accordance with one part of my invention devised an improved adjustable timin device comprising a flexible strap surroun%ing the ring and being secured at its ends to the flexible portions of the slitted arm, and preferably upon the tangential surfaces thereof, the flexible portions also having means to flex them for causing a tightening of the strap about the cam ring. As the flexible portions "are made -t o }-'approach each other Hind" t-he strap about the; cam ring tightened, it will be apparent that the perimetral length of the strap tends to shorten, the forces applied to. the ends thereof Being transmitted tangentially of the periphery of the cam ring and throughout the length of the strap so that radial pressure is applied to the- 'am ring evenly or uniformly for the full extent of the contactiiigsurfaces beifvveen'the strapan'd cam ring. hsi-anotherparfiofthe invention, whether or not'the-tiniing arrrr' has arc-shaped por tions'ahd tangential surfaces, the strap and thewam ring are provided with mutually er'igageable' means, preferably in the form of an annular groovein theperiphery of the am==ring and a-prej'ectlhn in the strapext'endihg into such groove, for maintaining thesmpmd rin in axial relation but to pgrma free re ativeang'ular movement.

y a further part of my invention, whether or net 'thetin'iing arm has areshaped portions and tangential surfaces, 'the flexible o'rtions 'o'f'the tllflliig arm are provideddv tl'i' projections which extend into, and are freely movable in, the groove formed in the cam ring so as to permit the universal elative' angular movement between the t mi'ng arnr-an d the'eam ring but preventing relative aitialmovement thereof.

In the "accompanyin "drawing illustratin'g the p refei red embo' iirient of the inventlO'Il: i

Fig. 1 is an end viewiin elevation with the cam" ring, umingamand binding strap; Fig. Qisa side v'ieivtlier'eiof; Fig. 3 is a top plan view thereof; Fig. 4 is a view in longitudinal section of the timing arm and binding strap and iv'ith the cam ring in plan; Fig. 5 is an end view 'of'the timing arm and t, binding strap, showing the projections tht eon; and Fig. 6 is a fragmentary sect'io'nml view on {an enlarged scale.

Referring more particu'lhrly to the draiving, an adjustable timing device constructed in accordance with my invention comprises a timing arm 1 being radially slitted to provide a slit 2 between the flexible portions 3 thereof the flexible portions being preferably provided with arcshaped ends 4, of the same curvature as the cam ring 5, for hearing against the periphery of the latter, as isclearly shown in Fig. 1. The flexihle portions 3 also *have faces 6 disposed in planes tannent to the periphery of the cam ring 5. The flexible orti'ons 3 are also provided with axially ahned-apertures 7 adapted to receive the binding. screw 8, one of the apertures being suitably threaded to co-opcrate 'with thethrea'ded portion of the screw. The cam ring has the usual cams 9 with which periodically engage the rotary deflectahle elements of a mechanical interrupter in the usual manner.

Upon the surfaces 6 are connected the ends 10 of a flexible strap '11, this "strap being relatively thin and of metal, the ends 10 being conveniently secured in place by means of screws 12.

The periphery of the cam ring 5',lS .preferably provided with an annular groove 13, the strap heing preferably provided with an indented projection 14 extending into the groove 13 so as to prevent relative axial movement between the cam ring 5 and the strap 11 but permitting free relative angular movement between the strap ulllll the cam ring, the projection being guided in the groove during such movement. The are shaped portions 4 are also preferablyypro vided with ridges or projections 15 11130 fitting into the'groove 13 for the purpose of preventing relative axial movement bet i'veen the arm 1 and the cam ring 5 but also permitting the free relative angular movement between the arm and the cam ring; anditlso for the purpose of steadying the timing arm laterally, the curved surface of the arcshaped ends seating squarely upon the periphery of the cam ring in aid thereof.

It will be apparent that when the screw 8 is loosened, the portions 3 of the arm '1 are expanded. The strap 11 then may he placed over the periphery of the cam ring with the projection 14 of the'strap and the projections 15 of the arm inserted in. the groove 13. With the parts in the latter position-, the arm 1 and thcstrap 11 may then'be rot-ated angularly about the axis of the cam ring to any desired adjusted angular relation. When the screw 8 is turned to'cause the flexing of the portions 3 toward each other, the ends 10 of the strap are thrown together or caused to move with a tendency to shorten the perimetral length of the strap about the cam ring 5; The forces acting on the ends of the'strap 11 act in lines or planes tangential to the cam ring 5, thus causing a mutual and equal pull upon the ends 10; and with a resultant uniform contraction of the flexible strap 11 upon the cam ring 5 and a uniform distribution of the contacting pressure between the surfaces of the strap 11 and :the ring 5. Inasmuch the pressure intensity is uniform at all points, a lunch greater total pressure may be applied to the cam ring, Without in. any Way affecting its true circular shape, and with sufficient engaging, pressure to prevent relative angular movement by the vibration of the parts durin: the operation of the engine.

It is not necessary to remove the interrupter housing from the magneto,iin'asrnuch as the device permits a =moveme nt' of 360 for adjustment at any angular position by the mere loosening ofthe binding screw,-the fiexihlestrap being on the periphery of the cam ring and of shbstantially the same circumference thereof.

Having thus described my invention what I claim is:

1. In an adjustable timing device for magnetos having an interrupter housing including a cam ring having a groove, the combination of a slitted timing arm having flexible portions adapted to engage said ring, a flexible strip surrounding said ring and'secured to the flexible portions of said slitted arm, means for flexing said flexible portions for tightening said strap about said ring, and a projection on said flexible portions of said arm extendin into and movable along said groove in said ring.

2. In an adjustable timing device for magnetos having an interrupter housing including a cam ring, the combination of a slitted timing arm having flexible portions adapted to engage said ring, a flexible strap surrounding said ring and secured at its ends to said flexible portions of said slitted arm, and means for flexing said flexible portions for tightening said strap about said ring, an annular groove in said ring and a projection in said strap extending in said groove for maintaining said strap and ring in fixed axial relation, said strap and projection being adapted to move angularly, and projections on said flexible portions of said arm extending into and movable along said groove in said ring.

3. In adjustable timing devices for magnetos, the combination of a slitted timing arm having flexible portions, a camring, said flexible portions being arc-shaped to engage the eriphery of said cam ring and having sur aces lying in planes tangent to said periphery of said cam ring, a strap surrounding said cam ring in smooth surface contact therewith and secured at its ends upon said surfaces of and to said flexible portions of said slitted arm, and means for flexl g said flexible portions for tightening said i rap about said cam ring.

4. IL adjustable timing devices for magnetos, the combination of anslitted timing arm having flexible portions, a cam ring, said flexible portions being arc-shaped to engage the periphery of said cam ring and having surfaces lying in planes tangent to said periphery of said cam ring, a strap surrounding said cam ring in smooth surface contact therewith and secured at its ends upon said surfaces of and to said flexible portions of said slitted arm, means for flexing said flexible portions for tightening said strap about said cam ring, and mutually engageable means on said strap and said ring for maintaining the same in fixed axial relation.

5. In adjustable timing devices for magnetos, the combination of a slitted timing arm having flexible portions, a cam'ring, said flexible portions being arc-shaped to engage the periphery of said cam ring and having surfaces lying in planes tangent to said seriphery of said cam ring, a strap surroun ing said cam ring in smooth surface contact therewith and secured at its ends upon said surfaces of and to said flexible portions of said slitted arm, means for flexing said flexible portions for tightening said strap about said cam ring, an annular groove in said ring and a projection in said strap extending in said groove for maintaining said strap and ring in fixed axial relation, said strap and projection being adapted to move singularly.

6. In an adjustable timing device for magnetos, the combination of a slitted timing arm having flexible portions, a cam ring having a groove, said flexible portions being arc-shaped to engage the periphery of said cam ring and having surfaces lying in planes tangent to said periphery of said cam ring, a strap surrounding said cam ring and secured upon said surfaces of said flexible portionsof said slitted arm, means for flexing said portions for tightening said strap about said camring, and a projection on said flexible portion of said arm extending into and movable along said groove in said ring.

7. Inadjustable timing devices for magnetos, the combination of a slitted timing arm having flexible portions, a cam ring, said flexible portions being arc-shaped to engage the periphery of said cam ring and having surfaces lying in planes tangent to said periphery of said cam ring, a strap surrounding said cam ring and secured at its ends upon said surfaces of and to said flexible portions of said slitted arm, means for flexing said flexible portions for tightening said strap about said cam ring, an annular groove in said ring and a projection in said strap extending in said groove for maintaining said strap and ring in fixed relation, said strap and projection being adapted to move angular-1y, and projections on said flexible portions of said arms extending into and movable along said groove in said ring.

In testimony whereof I aflix my signature.

C. AUGUST MAYER. 

